A traditional method of arranging such a vascular prosthesis consists of opening the abdominal wall from the sternum to the pubis, whereafter an incision is made along the full length of the blood vessel at the location of the unhealthy part. A suitable vascular prosthesis in the form of a tubular body of circular knitted textile of a similar diameter and length is subsequently sutured to the healthy ends of the blood vessel with suture needle and thread. The affected vessel wall is then preferably placed round the vascular prosthesis and subsequently closed.
It will be apparent that the above specified method involves a major operation which in practice can require more than three hours. Even more important than the total duration of the operation however is that the blood flow in the vessel has to be interrupted for a relatively long time, of sometimes more than an hour. This involves a serious danger of complications both during the operation and thereafter. It will moreover be apparent that the stated size of the operation wound in this operating method also results in a relatively great discomfort for the patient and adversely affects his recovery. There is also the risk of a certain leakage through the suture, so-called false aneurysms, which may in such cases necessitate the operation being repeated.
In order to obviate these drawbacks an alternative operation technique has been developed, wherein a vascular prosthesis is arranged at the desired location endovascularly, i.e. via the vascular system itself. Such an endovascular prosthesis generally comprises a tubular body, the wall of which is formed by a metal scaffold which is resilient and capable of expanding in radial direction. The endo-prosthesis is arranged in compressed state on a tip of a catheter and manoeuvred with the catheter via a relatively small incision in the groin or another suitable place to the weakened part of the blood vessel for treating. Having arrived at the desired location, a temporary envelope is pulled off the prosthesis or a balloon incorporated in the prosthesis is expanded, whereby the prosthesis expands from the compressed to an expanded state, wherein the prosthesis lies resiliently against an inner wall of the blood vessel. Initially only the expansion force of the prosthesis holds the prosthesis in its place, but in the course of time bodily tissue will be deposited on the prosthesis whereby in the long term it will ideally be completely embedded in the wall of the blood vessel.
Such an endovascular method undeniably entails less discomfort for the patient than the classical operating method and the circulation of blood through the blood vessels also remains largely undisturbed. Nevertheless, this method also has drawbacks. Apart from the relatively high cost of this treatment there is the drawback that the suturing of the prosthesis to the blood vessel is effected initially solely by the radial spring force of the prosthesis. There is a therefore a real danger that the prosthesis can be entrained to a greater or lesser degree by the blood flow. This danger is acknowledged in an example of a known endovascular prosthesis which is described in the International patent application no. 97/39687, wherein for this purpose the proximal side of the prosthesis is provided with a ring of fine hooks to anchor the prosthesis in the vessel wall. Because it must be possible to introduce the entire unit endovascularly, the dimensions and therewith the anchoring of these hooks are inevitably limited.
There is however also the risk that the blood will be able to find its way between the wall of the blood vessel and the prosthesis and then still exert the original pressure on the vessel wall. Such a case is referred to as an endo-leak. To remedy such a complication an operation in the traditional manner will still have to be performed, whereby all advantages of an endovascular treatment method are nullified. In order to prevent this in the case of the above stated example of a known endovascular vascular prosthesis, tensioning straps are arranged at the location of both the proximal and the distal end of the vascular prosthesis, after it has been introduced, for better fixation of the whole round the vessel wall. Such a fixation is also described in the case of the endovascular vascular prosthesis known from the American U.S. Pat. No. 5,764,274. However, such tensioning straps cannot be introduced endovascularly so that a classical operation is still required for this purpose. The tensioning member of the applied tensioning straps moreover provides an undesirable irregularity in the body which may adversely affect the biocompatibility of the whole.
Finally, as a result of their necessarily fragile construction, endovascular prostheses have been found in practice to be of limited durability, whereby for the time being the quality of the prosthesis cannot be fully guaranteed in the long term.